imx: imx8m: Imply CPU_IMX by default

The imx8_cpu driver is a CPU Driver that supports the i.MX8M
family, and when it is enabled, it acts as an alternative to
arch/arm/mach-imx/cpu.c, but the imx8_cpu supports the driver
model where cpu.c does not.  Imply this newer driver by default.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
1 file changed